Anyone here running a 3.85 final drive with a 5/6 speed? Currently running oem 3.62 but looking to upgrade to a clutch limited slip. For reference, I run both Nor/SoCal tracks and would like to avoid having to shift to 5th and rev over 8k. Any rpm/mph would be greatly appreciated. PFA, TIA!
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Can't really add much here from real world experience in this car (I'm still running stock gearing and only street drive this car)... but I'd probably put a 3.85 in over a 4.10 if I tracked mine.Build thread: Topaz Blue to Shark Blue -
I had 4.10 for a while with both the stock 6-speed and later ZF 5-speed. On any longer straight (COTA, Road America, Road Atlanta, etc.) I ran out of 5th gear. Swapping to 3.91 cured the gearing issue.
Feff
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I don’t think you’ll be able to avoid shifting to fifth with anything but a stock ratio unless west coast tracks are way slower than I think. I’m at the top of fourth with an 8200rpm redline on even the small-ish New England tracks. That’s about 120mph.Comment
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I have a 3.91. I usually shift at 7500-ish RPMs to increase engine life and better control temps so I'd usually shift into 5th gear or lift with a 3.62 and a 3.73.
The only real benefit of a 3.85 is you can get them at a lower cost from an E9X M3 6 speed.
Video with data - 3.91 on 275/40R17s
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Noted, Thank you all for the replies!Comment
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